Negative pressure dressing and method of using same

ABSTRACT

Disclosed herein are apparatuses and methods for treating a wound by applying reduced or negative pressure to the wound. The apparatus can include a wound cover, a fluid collection container, a vacuum pump, an inflation pump, and one or more conduits. The wound cover can be configured to move between at least a relatively rigid, generally raised position and a relatively flexible, generally collapsed position according to a predetermined program or in response to input from a user or one or more sensors. In some embodiments, the wound cover can be configured to move between at least the relatively rigid, generally raised position and the relatively flexible, generally collapsed position by adjusting the air pressure in one or more channels in the wound cover or by adjusting the length of piezoelectric or other length changing material supported by the wound cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to, and claims the benefit of, U.S.Provisional Patent Application No. 61/036,020, filed Mar. 12, 2008, theentirety of which is hereby incorporated by reference herein and made apart of the present disclosure.

BACKGROUND OF THE INVENTION

Field of the Invention

Certain embodiments of the present application relate to treating awound by applying reduced or negative pressure to the wound.

Description of the Related Art

The treatment of open or chronic wounds that are too large tospontaneously close or otherwise fail to heal has long been atroublesome area of the medical practice. Closure of an open woundrequires inward migration of surrounding epithelial and subcutaneoustissue. Some wounds, however, are sufficiently large or infected thatthey are unable to heal spontaneously. In such instances, a zone ofstasis in which localized edema restricts the flow of blood to theepithelial and subcutaneous tissue forms near the surface of the wound.Without sufficient blood flow, the wound is unable to successfully fightbacterial infection and is accordingly unable to close spontaneously.

An initial stage of wound healing is characterized by the formation ofgranulation tissue which is a matrix of collagen, fibronectin, andhyaluronic acid carrying macrophages, fibroblasts, and neovasculaturethat forms the basis for subsequent epithelialization of the wound.Infection and poor vascularization hinder the formation of granulationtissue within wounded tissue, thereby inhibiting wound healing. Ittherefore becomes desirable to provide a technique for increasing bloodcirculation within wounded tissue to promote spontaneous healing and toreduce infection.

Another problem encountered during the treatment of wounds is theselection of an appropriate technique for wound closure during thehealing process. Sutures are often used to apply force to adjacentviable tissue in order to induce the edges of a wound to migratetogether and heal. However, sutures apply a closure force to only a verysmall percentage of the area surrounding a wound. When there isscarring, edema, or insufficient tissue, the tension produced by thesutures can become great, causing excessive pressure to be exerted bythe sutures upon the tissue adjacent to each suture. As a result, theadjacent tissue often becomes ischemic, thereby rendering suturing oflarge wounds counterproductive. If the quantity or size of the suturesis increased to reduce the tension required of any single suture, thequantity of foreign material within the wound is concomitantly increasedand the wound is more apt to become infected. Additionally, the size ortype of a particular wound can prevent the use of sutures to promotewound closure. It therefore becomes desirable to provide an apparatusand method for closing a large wound that distributes a closure forceevenly about the periphery of the wound.

Wounds resulting from ischemia, or lack of blood flow, are also oftendifficult to heal since decreased blood flow to a wound can inhibitnormal immune reaction to fight infection. Patients that are bedriddenor otherwise non-ambulatory are susceptible to such ischemic wounds asdecubitus ulcers or pressure sores. Decubitus ulcers form as a result ofconstant compression of the skin surface and underlying tissue thusrestricting circulation. Since the patient is often unable to feel thewound or to move sufficiently to relieve the pressure, such wounds canbecome self-perpetuating. Although it is common to treat such woundswith flaps, the conditions that initially caused the wound can also workagainst successful flap attachment. Wheelchair-bound paraplegics, forexample, must still remain seated after treatment of pelvic pressuresores. It therefore becomes desirable to provide a treatment procedurefor ischemic wounds that can be conducted in situ upon an immobile orpartially mobile patient.

Other types of wounds in which ischemia leads to progressivedeterioration include partial thickness burns. A partial thickness burnis a burn in which the cell death due to thermal trauma does not extendbelow the deepest epidermal structures such as hair follicles, sweatglands, or sebaceous glands. The progression of partial thickness burnsto deeper burns is a major problem in burn therapy. The ability tocontrol or diminish the depth of burns greatly enhances the prognosisfor burn patients and decreases morbidity resulting from burns. Partialthickness burns are formed of a zone of coagulation, which encompassestissue killed by thermal injury, and a zone of stasis. The zone ofstasis is a layer of tissue immediately beneath the zone of coagulation.Cells within the zone of stasis are viable, but the blood flow is staticbecause of collapse of vascular structures due to localized edema.Unless blood flow is re-established within the zone of stasis soon afterinjury, the tissue within the zone of stasis also dies. The death oftissue within the zone of stasis is caused by lack of oxygen andnutrients, reperfusion injury (re-establishment of blood flow afterprolonged ischemia), and decreased migration of white blood cells to thezone resulting in bacterial proliferation. Again, it becomes desirableto provide a technique for treating burn wounds by enhancing bloodcirculation to the wounded tissue to inhibit burn penetration.

Negative pressure wound therapy has been around for many years and hasbeen proven to assist with the healing of wounds. There have been twodistinctive types of negative pressure wound covers, one is flexiblemembrane technology which is very common in the United States, and theother type is a rigid dome arrangement that has been used in Russiasince at least the mid 70's. Both have advantages and disadvantages inwound treatment therapy. For example, the flexible membraneconfiguration may be more advantageous for some types of wounds, duringcertain cycles of treatment, or even for certain portions of the bodythat have non-planar surface geometries. However, for certain wounds orduring certain cycles of the wound therapy, there may be advantages tousing rigid dome wound covers, such as increasing blood flow through thewound bed.

Additionally, as mentioned, there may be advantages to cycling betweenthe semi-rigid configuration and the collapsed configuration for oneparticular wound that is being treated. It may therefore be desirable tohave a wound cover that can change from a rigid configuration to acollapsed configuration easily and efficiently during the course oftreatment. However, the existing apparatuses available in the field donot have this ability. Therefore, there is a need for a wound cover thatcan be changed from the semi-rigid configuration to the collapsedconfiguration during the course of treatment.

SUMMARY OF THE INVENTION

Certain embodiments disclosed herein are directed to systems, methodsand apparatuses for wound therapy. However, it will be appreciated thatthe systems, methods and apparatuses may have application to otherfields. In certain preferred embodiments, the wounds being treated mayinclude, but are not limited to, acute and chronic wounds, orthopedictrauma wounds, and post-Cesarean wounds, to name a few.

In some embodiments, such wounds are treated using a negative pressurewound therapy apparatus that can comprise a wound cover, a fluidcollection container, a vacuum pump comprising a pump motor, and tubingor conduit. In addition, in some embodiments, the apparatus can includea pressure sensor that measures a pressure in the conduit. In someembodiments, one or more tubes of the conduit can channel a fluidbetween the wound cover, the fluid collection container, and the pump.In addition, in some embodiments, first and second control circuits canbe provided for controlling the pump motor without using a processor.

In some embodiments, such wounds are treated using a negative pressurewound therapy apparatus which can comprise a wound cover, a fluidcollection container, a pump unit comprising one or more vacuum and/orinflation pump motors, and conduit. In some embodiments, such wounds aretreated using an apparatus for covering a wound and facilitating theapplication of negative pressure wound therapy to the wound, comprisinga wound cover sized and configured to be placed over and enclose thewound so as to define a space between the wound cover and the wound andto maintain a reduced pressure in the space when reduced pressure isapplied to the space. In some embodiments, when the wound cover isplaced over and encloses the wound and negative pressure is applied tothe space, the wound cover can be configured to move between at least arelatively rigid, generally raised position and a relatively flexible,generally collapsed position wherein a volume of the space between thewound cover and the wound being generally greater in the generallyraised position than in the generally collapsed position.

In some embodiments, such wounds are treated using a wound cover forcovering a wound, wherein the wound cover can comprise a generallyflexible, fluid impermeable or semi-permeable cover or member and atleast one channel provided along at least a portion of the cover. Insome embodiments, the wound cover can be configured to become relativelyrigid during application of negative pressure to the space and when apositive pressure is supplied to the at least one channel, so as toincrease the volume of the space between the cover and the wound. Insome embodiments, the wound cover can be configured to become relativelyflexible during application of negative pressure to the space and whenthe positive pressure is removed from the at least one channel, so as tocollapse the wound cover in the approximate direction of the wound. Insome embodiments, the member can be sized and configured to be placedover and enclose the wound so as to define a space between the memberand the wound and to maintain a reduced pressure in the space whennegative pressure is applied to the space.

In some embodiments, such wounds are treated using a wound coverconfigured to enclose the wound, wherein the wound cover can comprise atleast one channel or pocket formed in the cover configured to provide anenclosed volume. In some embodiments, the at least one channel or pocketcan comprise at least one port or opening configured to permit fluid topass from a supply of fluid pressure into or out of the at least onechannel or pocket.

In some embodiments, such wounds are treated using an apparatus foradministering reduced pressure treatment to a wound on a body, theapparatus comprising a wound cover for covering a wound and facilitatingthe application of negative pressure wound therapy to the wound, a fluidcollection container, a vacuum pump, and a control device. In someembodiments, the wound cover can comprise a generally flexible, fluidimpermeable or semi-permeable cover sized and configured to be placedover and enclose the wound so as to create a space between the cover andthe wound, and a seal configured to seal at least a portion of themember to a portion of tissue surrounding the wound such that a reducedpressure is generally maintained in the space between the cover and thewound when the cover is placed over the wound and the space is suppliedwith reduced pressure.

In some embodiments, the member can be configured such that at least aportion of the member can be selectively moved between at least agenerally raised position and a generally collapsed position when themember is placed over the wound and the space is supplied with reducedpressure, and such that the volume of the space between the member andthe wound is greater in the generally raised position than in thegenerally collapsed position. In some embodiments, the vacuum pump canbe configured to provide reduced pressure to the space between themember and the wound, and can comprise a pump motor and one or moretubes configured to at least channel the reduced pressure from thevacuum pump to the space between the wound cover and the wound and tochannel a flow of fluid between the wound and the fluid collectioncontainer. In some embodiments, the control device can be configured soas to control the level of reduced pressure applied to the space betweenthe wound cover and the wound and to selectively moved at least aportion of the member between at least the generally raised position andthe generally collapsed position when the member is placed over thewound and the space is supplied with reduced pressure.

In some embodiments, such wounds are treated using a method comprisingthe steps of: providing a generally flexible, fluid impermeable orsemi-permeable cover sized and configured to be placed over and enclosethe wound so as to create a volume of space between the cover and thewound, sealing at least a portion of the cover to a portion of thepatient's skin surrounding the wound such that a desired level ofreduced pressure can be generally maintained in the volume between thecover and the wound when the cover is placed over the wound, providing afluid collection container, a vacuum pump, and one or more tubesconfigured to at least channel a flow of fluid between the cover, thefluid collection container, and the vacuum pump, controlling the vacuumpump to at least provide a predetermined level of reduced pressure tothe volume of space between the cover and the wound, and moving thecover between a generally raised position and a generally collapsedposition, the volume of the space between the cover and the wound beinggreater in the generally raised position than in the generally collapsedposition.

In some embodiments, such wounds are treated using a method comprisingthe steps of: placing a wound cover over the wound to enclose the wound,the wound cover being moveable between a first configuration that israised above the wound while the wound cover encloses the wound todefine an interior volume between the wound and the wound cover, and asecond configuration wherein the wound cover encloses the wound and iscollapsed toward the wound, and applying negative pressure to the woundwhile enclosed by the wound cover. In some embodiments, duringapplication of negative pressure to the wound, the wound cover canremain raised above the wound when in its first configuration, and cancollapse toward the wound when is in its second configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages will now be describedin connection with certain embodiments, in reference to the accompanyingdrawings. The illustrated embodiments, however, are merely examples andare not intended to be limiting. The following are brief descriptions ofthe drawings.

FIG. 1 is a schematic view of an embodiment of a negative pressure woundtherapy apparatus, comprising an embodiment of a wound cover.

FIG. 2 is a top view of a portion of an embodiment of a collectionsystem.

FIG. 3a is a section view of the wound cover of FIG. 1, taken throughline 3 a-3 a in FIG. 2, illustrating the wound cover in the raised orrigid configuration.

FIG. 3b is a section view of the wound cover of FIG. 1, taken throughline 3 b-3 b in FIG. 2, illustrating the wound cover in the deflated orcollapsed configuration.

FIG. 4a is a section view of the wound cover of FIG. 1, taken throughline 4 a-4 a in FIG. 2, illustrating the wound cover in the raisedconfiguration.

FIG. 4b is a section view of the wound cover of FIG. 1, taken throughline 4 b-4 b in FIG. 2, illustrating the wound cover in the deflatedconfiguration.

FIG. 5 is a top view of another embodiment of a wound cover.

FIG. 6A is a section view of the wound cover of FIG. 5, taken throughline 6A-6A in FIG. 5, illustrating the wound cover of FIG. 5 in therigid or raised configuration.

FIG. 6B is an enlarged section view of a portion of the wound cover ofFIG. 5, defined by curve 6B-6B in FIG. 6A.

FIG. 7 is a top view of another embodiment of a wound cover.

FIG. 8 is a section view of the wound cover of FIG. 7, taken throughline 8-8 in FIG. 7, illustrating the wound cover of FIG. 7 in the raisedconfiguration.

FIG. 9 is a top view of another embodiment of a wound cover.

FIG. 10A is a section view of the wound cover of FIG. 9, taken throughline 10A-10A in FIG. 9, illustrating the wound cover of FIG. 9 in thecollapsed configuration.

FIG. 10B is a section view of the wound cover of FIG. 9, taken throughline 10B-10B in FIG. 9, illustrating the wound cover of FIG. 9 in theraised configuration.

FIG. 11 is a schematic representation a portion of another embodiment ofa negative pressure wound therapy apparatus, illustrating the woundcover in the deflated configuration.

FIG. 12 is a schematic representation the portion of the negativepressure wound therapy apparatus shown in FIG. 11, illustrating thewound cover in the semi-rigid configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is now directed to certain specificembodiments of the disclosure. In this description, reference is made tothe drawings wherein like parts are designated with like numeralsthroughout the description and the drawings.

Preferred embodiments disclosed herein relate to wound therapy for ahuman or animal body. Therefore, any reference to a wound herein canrefer to a wound on a human or animal body, and any reference to a bodyherein can refer to a human or animal body. The term “wound” as usedherein, in addition to having its broad ordinary meaning, includes anybody part of a patient that can be treated using reduced pressure.Wounds include, but are not limited to, open wounds, pressure sores,ulcers and burns. Treatment of such wounds can be performed usingnegative pressure wound therapy, wherein a reduced or negative pressurecan be applied to the wound to facilitate and promote healing of thewound. Additional descriptions of devices, methods and systems that canbe used for wound therapy are found in U.S. Pat. No. 7,128,735 (entitled“Reduced Pressure Wound Treatment Appliance”), the entirety of which ishereby incorporated by reference and made a part of the presentdisclosure. It will also be appreciated that the negative pressuresystems and methods as disclosed herein can be applied to other parts ofthe body, and are not necessarily limited to treatment of wounds.

The application of reduced or negative pressure to a wound can providesuch benefits as faster healing, increased blood flow, decrease inbacterial burden, increase in the rate of granulation tissue formation,removal of exudate and slough from the wound, alleviation ofinterstitial edema, stimulation of the proliferation of fibroblasts,stimulation of the proliferation of endothelial cells, closure ofchronic open wounds, inhibition of burn penetration, and enhancement offlap and graft attachment, among other benefits. Some or all of thesebenefits can be improved by the apparatus disclosed herein. Wounds thathave exhibited positive response to treatment by the application ofnegative pressure include infected open wounds, decubitus ulcers,dehisced incisions, partial thickness burns, and various lesions towhich flaps or grafts have been attached.

In particular, the embodiments disclosed herein relate to a wound coverthat can be configurable so as to be either a rigid type wound cover(that can be rigid enough so as to define an air space between the woundcover and the wound) or a flexible type of wound cover (that can becollapsible so as to conform to the shape of the wound site) so as tochange the volume of space between the wound cover and the wound, amongother things. As will be described in greater detail below, in someembodiments, the wound cover is changed from the rigid or raised type tothe flexible type by adjusting the structural rigidity and/or geometryof the wound cover. In some embodiments, the level of reduced ornegative pressure applied to the wound can remain the same orsubstantially same (e.g., within approximately 99% to 85% of the levelof applied reduced or negative pressure) when the cover is moved betweenthe raised and collapsed configurations. Thus, the embodiments of thewound cover disclosed herein enable medical professionals to apply therigid dome technology and/or the flexible membrane technology using thesame wound cover. Further, the embodiments of the wound cover enablemedical practitioners to cycle from a rigid or raised type wound coverthat does not contact the wound bed or exert any physical pressurethereon, to a flexible type wound cover that can exert a small amount ofphysical contact pressure on the wound bed during the course of woundtreatment. As will be discussed below, by allowing the wound cover to becycled between the two types described above, the user and/orpractitioner is able to optimize the negative pressure wound treatment,i.e., choose the most appropriate wound cover structure, at any pointthrough out the healing duration

In some embodiments, the wound cover is changed from a flexible type toa rigid type wound cover by providing a positive pressure to channelsformed in the wound cover and, hence, inflating such channels so as toprovide greater rigidity to the wound cover. In these embodiments, thewound cover will be configured such that, as the channels are inflated,the wound cover rises above the wound bed so as to form a volume ofspace between the wound cover and the wound bed. Thus, in theseembodiments, the rigid dome technology is achieved when the wound coveris in the semi-rigid configuration, and the collapsed configuration isachieved when the wound cover is in the deflated configuration.

FIG. 1 is a schematic view of an embodiment of a negative pressure woundtherapy apparatus 20, that can be configured to treat a wound byapplication of reduced or negative pressure (i.e., below atmosphericpressure) to a wound site 22 in a controlled manner for a predeterminedamount of time. As illustrated in FIG. 1, the negative pressure woundtherapy apparatus 20 can comprise a wound cover 24 (which can bereferred to as a dressing) for enclosing a wound site 22 and providing afluid-tight or substantially gas-tight enclosure over the wound site 22to effect treatment of a wound site 22 with reduced or negativepressure. For the purpose of creating suction within the wound cover 24,the wound cover 24 is connected to a vacuum system 26 to provide asource of suction or reduced pressure for the sealed wound cover 24 atthe wound site 22. Between the wound cover 24 and the vacuum system 26is a fluid collection system 28 for intercepting and retaining exudatethat is aspirated from the wound site 22. Note that, any of thematerials, sizes, geometries, or other configurations or featuresdescribed with respect to any wound covers in this application can beapplied, as suitable, to any embodiments of the wound cover 24 disclosedherein.

Predetermined amounts of suction or reduced pressure below atmosphericpressure can be provided by the vacuum pump 30. A control device 32 cancontrol the vacuum pump 30 so as to control the amount of suction thatis provided to the wound cover 24 and wound site 22. In someembodiments, the control device 32 can be configured to operate withouta processor. For example, the control circuit and other aspects of theapparatuses and methods in International Patent Application PublicationNo. WO2008048481, titled “Improved Control Circuit And Method ForNegative Pressure Wound Treatment Apparatus,” filed on Oct. 13, 2006,can be used to control the pump motor disclosed herein. Additionally,any of the configurations described in the above-mentioned WO2008048481application regarding pressure sensors, the control of such pressuresensors, and/or other aspects of the apparatuses and methods therein canbe used with the apparatus described in the present application, andInternational Patent Application Publication No. WO2008048481 is herebyincorporated by reference in its entirety as if fully set forth herein.

In some embodiments, the control device 32 can comprise a processor thatenables the control device 32 to control the vacuum pump 30, or, asdescribed below, the wound cover 24 or other components comprising theapparatus 20. Furthermore, the control device 32 can be a computer, dataprocessor, or other controller having any suitable device such as, butnot limited to, a processor, for controlling the pump motors and/orother components that are disclosed herein, or for receiving or changingdata, or for any other function suitable for the apparatus 20.

A filter 34, such as a micropore or pathogen filter, or any othersuitable component that can be configured to filter pathogenic microbes,aerosols, or other contaminants, can be attached to the exhaust of thevacuum pump 30 to prevent potentially pathogenic microbes, aerosols, orother contaminants from the wound site 22 from being vented to theatmosphere by the vacuum pump 30. In addition, a filter, such as amicropore filter, can be attached to the inlet of the vacuum pump 30,for example, at the second port 44 positioned on the top of thecontainer 38, to prevent potentially pathogenic microbes, aerosols, orother contaminants from contaminating the wound the site 22 and/or thepump 30.

In some embodiments, the vacuum system 26 of the negative pressure woundtherapy apparatus 20 can comprise two or more vacuum pumps 30 that canbe connected in parallel to the collection system or wound cover 24 withtubing or conduit 36. The additional pump 30 can ensure a higher levelof safety, performance, and product quality by providing pump redundancyto prevent vacuum system failure in the event that a single pump fails,in addition to more quickly and efficiently providing suction.

It should be noted that any of a wide range of vacuum pumps, pumpcontrollers, fluid collection system, or wound packing elements ormaterials presently known in the art or developed in the future can beconfigured to be integrated into the negative pressure wound therapyapparatus 20 disclosed herein. Thus, in addition to the components andfeatures disclosed herein, the embodiments of the negative pressurewound therapy apparatus 20 can have any of the features and componentsthat are known in the art or that are suitable for such system. Forexample, one available type of apparatus that can be used to provide thenecessary reduced pressure is the EZCARE Negative Pressure Systemavailable from Smith & Nephew.

As illustrated in FIG. 1, the sealed fluid collection system 28 (whichcan be generally gas-tight) can be comprised of a fluid-impermeablecollection container 38 for containing and temporarily storing thecollected exudate. The container 38 can have a shutoff mechanism 40 andcan be of any size and shape suitable for intercepting and retaining apredetermined amount of exudate. The illustrated container 38 can have afirst port 42 and a second port 44 positioned on the top of thecontainer 38. The first port 42 can enable suction to be applied to thewound cover 24 through the conduit 46 and also can enable exudate fromthe wound site 22 to be drained into the container 38. The second port44 can be provided to enable the application of suction from the vacuumpump 30 to the container 38 through vacuum line 36.

The conduit 36, 40, and any other conduit used with the apparatus 20 orany other apparatus disclosed herein, can be sufficiently flexible topermit movement of the conduit 36 as the patient's body moves, whilebeing sufficiently rigid to resist constriction when reduced pressure issupplied to the wound cover 24 or when an external pressure is appliedto the outside of the conduit, such as from the patient or otherwise.Furthermore, the conduit 36 can have multiple chambers or lumens, or canbe comprised of multiple sections of tubing that can be arranged inparallel to increase the volume of air that is supplied to or from thewound cover 24 and/or the channels 50, as is discussed below.

In some embodiments, an inflation system 48 can be configured to produceat least a source of positive pressure (i.e., above atmosphericpressure) to channels 50 of the wound cover 24 so as to controllablyinflate the channels 50, as described further below. In this manner, auser or practitioner can change the hybrid wound cover 24 from aflexible type dressing or cover configuration to a rigid type dressingor cover configuration. For example, in some embodiments, a pump motorcan be used to inflate a network of channels formed in the wound coverso as to increase the structural rigidity of the wound cover such thatthe wound cover forms a volume of space over the wound bed and is nolonger in contact with the wound bed. In the semi-rigid configuration,the wound cover can be sufficiently rigid so as to not collapse whennegative pressure is applied to the volume of space between the woundcover and the wound. By reducing the pressure within the network ofchannels 50, the wound cover 24 can be collapsed over the wound byapplying a negative pressure within the volume between the wound coverand the wound. In this fashion, the wound cover can be cyclically orselectively changed from a rigid to a flexible type wound cover.

As shown in FIG. 1, the hybrid wound cover 24 is in the generallycollapsed arrangement, so that it is most similar to the flexible typedressing or cover described above. As illustrated, the inflation system48 can comprise a pressure pump 52 that is configured to supply apositive pressure to the channels 50 in the wound cover 24 throughconduit 54. Similarly, to enable the wound cover 24 to change from therigid type configuration to the flexible type configuration, thepressure pump 52 can be configured so as to reduce the pressure withinthe channels 50, which can be done by suctioning air from the channels50. Thus, similar to the vacuum pump 30, the pressure pump 52 can becontrolled by the control device 32 so as to control the amount ofpositive pressure that is supplied by the pressure pump 52 to thechannels 50 of the wound cover 24, as well as to control the deflationof the channels 50 when desired. Thus, in some embodiments, the pressurepump 52 can be configured to provide a negative or reduced pressure tothe channels 50. Some embodiments of the apparatus 20 further comprisepressure sensors located in the conduit 54, channels 50, or in othersuitable positions to monitor the positive pressure provided by thepressure pump 52 to the channels 50 and assist with the control of thepressure pump 52.

In some embodiments, the apparatus 20 can further comprise a filter (notillustrated) that can be configured to filter the air that is suppliedby the pressure pump 52 to the wound cover 24. In some embodiments, thefilter can be a micropore or pathogen filter or any other suitablecomponent that can be configured to filter pathogenic microbes,aerosols, or other contaminants from the air flowing from the pressurepump 52 to the wound cover 24 so that sterile air is provided by thepressure pump 52 to the wound cover 24. In some embodiments, this canensure that the wound site 22 will not be exposed to any contaminantsfrom the air supplied by the pressure pump 52 in the event that there isany leakage of air from the channels 50 into the space between the woundcover 24 and the wound site 22.

In some embodiments, the wound cover 24 and the conduit 54 can beconfigured to comprise a removable connector 56 so as to allow theconduit 54 to be removably connectable to the channel 50. Alternatively,the wound cover 24 can comprise one or more ports (not illustrated) forconnecting the conduit 54 to the wound cover 24. Similarly, in someembodiments, the channels 50 of the wound cover 24 can comprise one ormore ports (not illustrated) for connecting the conduit 54 to thechannels 50.

As illustrated in FIG. 1, the wound cover 24 can be affixed to thehealthy skin 58 around the periphery of the wound site 22 with adhesive60 so as to provide a generally gas-tight or fluid-tight enclosure overthe wound site 22. Note that, while a perfect seal is desirable, it isnot necessary. The apparatus 20 disclosed herein can function suitablywell for the intended purpose even if the seal between the healthy skin58 and a wound cover 24 is not perfectly fluid or gas tight. In someembodiments, the wound cover 24 can be configured so as to maintain asufficient seal between the wound cover 24 and the healthy skin 58surrounding the wound 22 when a supply of negative pressure is providedto a wound site 22 under a wound cover 24, preferably without theapplication of an adhesive or other sealing member or material betweenthe wound cover 24 and healthy skin 58 surrounding the wound 22. Thus,in some embodiments, the supply of negative pressure to the wound site22 surrounded by the wound cover 24 can be sufficient to create asufficiently fluid and gas tight seal between the wound cover 24 andhealthy skin 58 surrounding the 122.

However, in some embodiments, the wound cover 24 can comprise anadhesive backing or layer 60, or other member or substance such aslanolin to facilitate the formation of a seal between the wound cover 24and healthy skin 58 surrounding the wound 22. In some embodiments, suchsubstances or materials can be positioned between at least a portion ofthe wound cover 24 and the healthy skin 58 around wound site 22. In someembodiments, the adhesive backing or layer 60 can be placed around theperimeter of the side of the wound cover 24 that will be placed againstthe healthy skin 58, so that he adhesive will not inadvertently comeinto contact with the wound site 22. The seal can be approximatelygas-tight or fluid-tight over the wound site 22. The adhesive 60 canhave sufficient adhesion to form a fluid-tight or gas-tight seal aroundthe periphery of the wound site 22 and to hold the wound cover 24 insealed contact with the skin 58 during the application of reducedpressure, as well as during application of positive pressure to thechannels 50. The wound cover 24 can also provide a gas-tight seal aroundthe conduit 46 at the feed through location 62 where the conduit 46emerges from beneath the wound cover 24.

In some embodiments, the conduit 46 can be removably attached to thewound cover 24 through a port (not shown) positioned on the wound cover24. In some embodiments, such a port can be integrally formed with thewound cover 24 or can be formed in a separate process and attached tothe wound cover 24. In either configuration, once attached to theconduit 46, the port can provide a generally fluid-tight connectionbetween the conduit 46 and the wound cover 24. In some embodiments,connection can be removable so that the conduit 46 can be removed fromthe port or the wound cover 24. Additional descriptions of wound coverscomprising ports can be found in U.S. Patent Application Publication No.2005/0261642 A1 (application Ser. No. 11/064,813), titled “FlexibleReduced Pressure Wound Treatment Appliance” and filed on Feb. 24, 2005,the entirety of which is hereby incorporated by reference and made apart of the present disclosure as if fully set forth herein.

As discussed above, some embodiments of the apparatus 20 and wound cover24 can be configured so as to not require any adhesive to provide asufficiently fluid-tight seal between wound cover 24 and the healthyskin 58 surrounding the wound. In these embodiments, the wound cover 24can be configured such that the application of negative pressure to thewound site 22 creates a sufficient seal between the wound cover 24 andthe patient's body so as to maintain a sufficiently fluid and gas tightseal over the wound site 22. Additionally, in some embodiments, othersubstances that promote a sufficiently fluid-tight seal without havingadhesive effects, such as Lanolin or any other suitable substance, canbe used.

In some embodiments, the apparatus 20 can also comprise a suction drainpositioned within or adjacent to the wound site 22. The suction draincan comprise a bottom drain portion (such as, but not limited to, aconduit segment 46 a described below and illustrated in FIG. 1)extending into the wound site 22 under the wound cover 24. The drainportion can be attached to the end of the conduit 46 and can becomprised of polymer tubing that is flexible enough to allow the conduitto easily bend, but rigid enough to prevent the conduit from collapsingduring use. In other embodiments, portions of the drain portion can becomprised of other materials, such as flexible or semi-rigid polymers,plastics, rubber, silicone, or combinations of such materials. In yetother embodiments, the drain portion can have different cross-sectionalshapes, such as elliptical, square, rectangular, pentagonal, hexagonal,or other shapes. Additionally, in some embodiments, the drain portioncan have openings or perforations along a portion of the length thereofthrough which exudate or other material that is removed from the woundsite 22 can pass.

In some embodiments, as in the embodiment illustrated in FIG. 1, theapparatus 20 can also comprise an absorbable matrix 64 or other woundpacking material such as gauze (non-adherent, anti-microbial, orotherwise), open cell foam, sea sponges, or other suitable or desirableobjects or materials that can allow the transmission of suction withinthe wound site 22. In further embodiments, the matrix can benon-bioabsorbable, as is known in the art. In the illustratedembodiment, the tube segment 46 a embedded within the absorbable matrix48 can have at least one side port 47 positioned within the interior ofthe absorbable matrix 64 to enable a substantially uniform applicationof reduced pressure throughout the enclosure. In other embodiments, thetube segment 46 a can comprise a plurality of side ports 47 positionedwithin the interior of the absorbable matrix 64. The absorbable matrix64 can be comprised from any material suitable for negative pressurewound therapy, such as is described in U.S. Patent ApplicationPublication No. US 2004/0073151 A1, titled “Reduced Pressure WoundTreatment Appliance,” which is hereby incorporated by reference in itsentirety as if fully set forth herein. Embedding the open end of segment46 a of conduit 46 within the interior of the absorbable matrix 64 canpermit the absorbable matrix 64 to function as a shield to help preventthe wound cover 24 from being inadvertently sucked into sealingengagement with the open end of the tube, which can plug the tube 46 andrestrict the flow of reduced pressure to the wound cover 24. Inaddition, the absorbable matrix 64 can encourage the growth of tissue inthe area of the wound 22 into the matrix 64 and can hold the wound cover24 generally out of contact with the wound 22 during the application ofsuction to the enclosure.

FIG. 2 is a top view of an embodiment of the wound cover 24. Asillustrated in FIG. 2, the wound cover 24 can be positioned over thewound site 22 such that the adhesive 60 on the wound cover 24 adheresthe wound cover 24 to the healthy skin 58 surrounding the wound site 22.As illustrated in FIG. 2, the conduit 54 can be interconnected with thechannels 50 so as to be a fluid communication with the channels 50. Insome embodiments, the conduit 50 can be connected to the channels 50using a typical connector (not illustrated) of the type found in thefield. In some embodiments, the wound cover 24 can be formed so that apredetermined length of conduit 54 is integrally formed with thechannels 50 on the wound cover 24. In such embodiments, thepredetermined length of conduit 54 provided with the wound cover 24 canbe long enough so as to be interconnectable with the pressure pump 52.

As shown in FIG. 2, the channels 50 of this embodiment can be arrangedin a rectangular fashion so as to define a plurality of rows. In theillustrated arrangement, the wound cover 24 can comprise five rows ofchannels 50 arranged in a direction that is parallel with the line3A-3A, and three rows of channels 50 arranged in a direction that isparallel with the line 4A-4A. However, the wound cover 24 is not limitedto this arrangement, but can define any number of rows of channels 50suitable for the size of the wound cover 24, the size of the wound, thelocation of the wound on the body, the desired amount of rigidity of thewound cover 24 when it is in the raised position or configuration, orany other characteristics related to the performance of the wound cover24. The wound cover 24 can be formed in any of a wide range of sizes andshapes so that a particularly beneficial size of the wound cover 24 isavailable for any wound in a wide range of sizes, shapes, and locationson the body.

In some embodiments, the wound cover 24 can comprise a greater or lessernumber of rows of channels 50 in either direction as compared to theembodiments illustrated or described herein. For example, in someembodiments, the wound cover 24 can have an approximately squareperimeter and comprise six or more rows of channels 50 arranged in adirection that is parallel with the line 3A-3A, and six or more rows ofchannels 50 arranged in a direction that is parallel with the line4A-4A. Additionally, in some embodiments, the channels can be arrangedin any suitable geometric pattern. For example, without limitation, thechannels 50 can be interconnected so as to efficiently allow air to flowinto and out of all of the channels 50. In some embodiments, the woundcover 24 and channels 50 (or any wound cover or channel configurationdisclosed herein) can define a square, circular, triangular, or ovularshaped, or any other desired or suitable shape.

In some embodiments, the channel or channels 50 can cover approximatelythe entire cover or approximately the entire wound bed. In someembodiments, the cover can have only one substantially enclosed channelor pocket that covers approximately all of the wound cover 24 and/orwound bed, with the only opening(s) therein being in the one or moreports or one or more other openings that allow air to flow from the airpressure supply conduit(s) into or out of the channel or pocket (but,otherwise, the channel or pocket can be fully enclosed). In someembodiments, the substantially enclosed channel or pocket can be formedbetween two layers of impermeable or semi-impermeable materialcomprising the wound cover 24, the two layers being laminated orotherwise sealingly joined around the periphery thereof. The two layerscan have internal walls, connections, or other features configured toprovide one or more connection points between the two layers within theperiphery of the two layers.

Additionally, in some embodiments, the shape of the wound cover 24 canbe different than the shape of the network of channels 50. For example,without limitation, the wound cover 24 can define a square or circularperimeter, whereas the channels 50 can form a crisscross pattern on thewound cover 24, or any other pattern suitable to allow the wound cover24 to preferably to change between the raised (or rigid) and collapsed(or flexible) configurations.

In general, the channels 50 can be configured and arranged on the woundcover 24 so as to provide the wound cover 24 with a desired shape or toallow the wound cover 24 to take a desired shape, both in the rigidconfiguration or position and of the collapsed configuration orposition. The channels 50 can be configured so as to define any suitablecross-sectional shape when the channels 50 are in a generally inflatedconfiguration or state. For example, in some embodiments, the channelscan define a round, ovular, triangular, square, rectangular, pentagonal,or other suitable shape. Further, the wall thickness of the materialforming a walls of the channels 50 can be selected or determined basedon factors such as, but not limited to, the material used to form thechannels 50, the shape of the wound cover 24, the contour of the skinthat the wound cover 24 is to be adhered to, the desired amount ofrigidity of the wound cover 24 in the dome configuration or position,the desired amount of flexibility of the wound cover 24 in the collapsedconfiguration or position, or other factors. In some embodiments, thechannels 50 can be configured such that, when the channels 50 aredeflated, the deflated channels 50 are sufficiently compliant so thatthe wound cover 24 can conform to the wound site 22 or any wound packingmaterials placed in the wound site 22, while being sufficiently rigid soas to position wound cover 24 in the dome or raised position when thechannels 50 are inflated.

FIG. 3A is a section view of the wound cover 24 illustrated in FIG. 2,taken through line 3 a-3 a in FIG. 2, illustrating an embodiment of thewound cover 24 in the raised or rigid configuration (also referred toherein as the raised or rigid dome position, or raised position). FIG.4a is a section view of the wound cover 24 taken through line 4 a-4 a inFIG. 2, also illustrating an embodiment of the wound cover 24 in theraised configuration. In the illustrated configuration, the wound cover24 can comprise a flexible sheet member 66 and at least one channel 50formed on, or adhered to, the top surface of the flexible sheet member66. The at least one channel 50 can also be integrally formed with theflexible sheet member 66. The wound cover 24 can be configured togenerally maintain a reduced pressure in the space 68 when suction isapplied to the space 68.

In some embodiments, the sheet or member 66 can be sized and configuredto be placed over and enclose the wound 22 so as to define a space 68between the flexible sheet member 66 and the wound 22 when the woundcover 24 is in the raised configuration. In some embodiments, the member66 (that can be flexible) illustrated in FIG. 3A, or any flexible memberof any embodiment of the wound cover disclosed herein, can be sized andconfigured so as to be generally unstretched when the flexible membraneis in the raised configuration, as illustrated in FIG. 3A. Inparticular, in some embodiments, the flexible sheet member 66 can besized and shaped so as to define a concave and/or convex shape when theflexible sheet member 66 is in an unstretched state. In thisconfiguration, because the member 66 preferably does not have to bestretched when the wound cover is changed from the collapsedconfiguration to the raised configuration, a smaller force can berequired to be exerted by the channels 50 on the member 66 to raise themember 66 to the raised configuration. Additionally, in thisconfiguration, the wound cover 24 can be better arranged to conform toany depressions in the wound bed. As a result, the wound cover can bemore easily changed from the collapsed configuration to the rigid,raised configuration, and will be better equipped to create an airspacebetween the wound cover and the wound bed in the arranged configuration,and the better equipped to conform to the wound bed and the flexibleconfiguration.

In the embodiment of the wound cover 24 wherein the wound cover 24 is inthe raised or rigid configuration, as illustrated in FIG. 3a , apositive supply of pressure has preferably been supplied by the pressurepump 52 to the channels 50 of the wound cover 24 so as to cause thewound cover 24 to rise above the wound site 22 and create a space 68between the wound cover 24 and the wound site 22. As can be seen in FIG.3a , a series of openings 50 a can interconnect the channels 50 so thatthe channels 50 form a continuous network. As mentioned, in theillustrated embodiment, the channels 50 can be formed on the top, outersurface of the flexible sheet or member 66. However, the wound cover 24is not limited to this configuration. The channels 50 and wound cover 24can be of any suitable size or configuration, or located at any suitableposition to selectively provide rigid support to an otherwise generallyflexible wound cover 24, so as to selectively cause the wound cover 24,to be raised above the wound site 22 when desired. In the raisedconfiguration, the wound cover 24 can be sufficiently rigid to withstandcollapse or buckling, so as to maintain the volume of space 68 betweenthe member 66 and the wound site 22 when negative pressure is suppliedto the wound site 22 through conduit 46.

In any embodiments disclosed herein, the channels 50 can be sized,structured, or otherwise configured to have a pre-memorized shape orcurvature that can bias the wound cover 24 to a dome type configurationor position wherein the volume of space is created between the woundcover 24 and the wound site 22 when the channels 50 are inflated orotherwise activated. Conversely, in some embodiments, the channels 50can be sized, structured, or otherwise configured so that, when thepositive pressure has been generally removed from the channels 50, thechannels 50 do not bias the wound cover 24 to a dome type configurationor position but, rather, allow the wound cover 24 to conform to theshape of the wound site 22 and/or the wound packing material that is inthe wound site 22. Accordingly, in some embodiments, when the positivepressure has been generally removed from the channels 50, the channels50 can appear crumpled or otherwise unstretched.

FIG. 3b is a section view of the wound cover 24 illustrated in FIG. 1,taken through line 3 b-3 b in FIG. 2, illustrating an embodiment of thewound cover 24 in the deflated or collapsed configuration (also referredto herein as the deflated or collapsed position) wherein the wound cover24 most closely resembles a flexible membrane wound cover. FIG. 4b is asection view of the wound cover 24 taken through line 4 b-4 b in FIG. 2,also illustrating an embodiment of the wound cover 24 in the deflatedconfiguration. In the deflated configuration of the embodimentillustrated in FIG. 3b , the channels 50 can be deflated so that they nolonger rigidly support the wound cover 24 over the wound site 22. Thus,in this configuration, the channels 50 can be flexible enough so thatthey do not substantially impede the flexibility of the wound cover 24.Accordingly, the supply of negative pressure via conduit 46 can causethe wound cover 24 to flexibly collapse over the wound site 22, as isalso illustrated in FIG. 1. Additionally, as discussed above and shownin FIG. 1, a wound packing material such as gauze or an absorbablematrix can be positioned over the wound site 22, below the wound cover24. When such wound cover is included, the wound cover 24 can beconfigured to flexibly collapse over such wound packing material.

As illustrated in FIGS. 2-4B, the thickness of each of the walls of thechannels 50 can be designed so that the channels 50 can be flexible whenthe channels 50 are deflated, as shown in FIG. 3B, but sufficientlyrigid to support the wound cover 24 when the channels 50 are inflated.Further, in the embodiment illustrated in FIG. 2, the channels 50 can bearranged on the flexible sheet 66 in a rectangular shape such that thechannels 50 form a perimeter shape that matches, but is slightlyundersized as compared to, the perimeter of the flexible sheet 66. Asdescribed above, the internal openings 50 a can create a network ofinternal air passageways that allow the air supply through the conduit54 to preferably completely fill all the channels 50 in an efficientmanner. In some embodiments, the channels 50 can be formed such that theinternal air space 50 a is greater near the middle of the channel 50than at the end portion of the channel 50, i.e., such that internalheight of the channels 50 (represented by the dimension “t” in FIG. 3A)is greater near the middle portion of the channels 50 than at the endportions of the channel 50. This can provide greater structural rigidityto the wound cover 24, when the channels 50 are in the inflatedconfiguration.

As stated above, in some embodiments, when the channels 50 are deflated,such as is illustrated in FIG. 3B, the material comprising the channels50 can be unstretched and somewhat crumpled, such as in anaccordion-like fashion (not shown). In this configuration, the channels50 and the wound cover 24 can be more flexible and pliable, so that thenegative pressure supplied to the space 68 will cause the wound cover 24to be drawn toward the wound site 22. When such channels 50 areinflated, the material comprising the channels 50 can then be expandedand stretched, which can bias the wound cover 24 to the expanded orraised configuration or position.

In some embodiments, the apparatus 20 can be configured so that, beforethe wound cover 24 is changed from the collapsed configuration to theraised configuration, a positive pressure is supplied for a shortduration of time to the volume of space 68 between the wound cover 24and the wound site 22. The positive pressure supplied to the space 68will help ensure that, as the pressure within the channels 50 is beingincreased and, hence, the wound cover 24 is becoming more rigid, thewound cover 24 expands to form a rigid enclosure over the wound site 22so as to increase the volume of space 68 over the wound site 22 insteadof buckling against the wound site 22. After the channels 50 have beensufficiently pressurized so as to form a rigid wound enclosure 24, thepressure within the space 68 can then be reduced to a level that isbeneficial to the healing of the wound site 22. This positive pressureloading can have other benefits also. In other embodiments, the size andgeometric configuration of the channels 50 will help ensure that, as thechannels 50 are being pressurized, the wound cover 24 expands upwardlyaway from the wound site 22, despite the magnitude of negative pressurethat can be present in the volume of space 68.

The channels 50 can be formed integrally with the member 66, or can beformed in a separate process and bonded with adhesive to, fused with, orotherwise adhered to the outer surface of the member 66. In someembodiments, the channels 50 can be positioned or formed on the insidesurface of the member 66 so as to be within the interior space 68between the member 66 and the wound bed 22. In some embodiments, themember 66 can be formed between symmetrical, opposing channels 50. Insome embodiments, as in the illustrated embodiments the member 66 can beformed around the outside perimeter of the network of channels 50 so asto form a perimeter around the channels 50 that can be bonded to thehealthy skin 58 surrounding the wound site 22.

The channels 50 and/or member 66 of the wound cover 24 can comprise anysuitable medical grade flexible material that is currently known in theart or that may be developed in the art in the future. Such material canbe fluid-impermeable or semi-permeable and otherwise suitable forpurposes of wound treatment (e.g., can be sterilized or cleaned and doesnot absorb significant amounts of wound exudate), and is capable offorming an approximately liquid and/or fluid and gas tight seal with thesurface of the skin around the site of the wound, as is discussed above.In some embodiments, the wound cover 24 can be formed from polyurethane.In some embodiments, the wound cover 24 can be formed from materialssuch as, but not limited to, rubber including neoprene, and/or flexiblepolymer materials such as silicone, silicone blends, siliconesubstitutes, polyester, vinyl, polyimide, polyethylene napthalate,polycarbonates, polyester-polycarbonate blends, polyurethane, ethylvinyl acetate, or any other similar or suitable polymer or combinationsof all such materials. The channels 50 can be formed from any of thematerials comprising the member 66, or any other suitable material.

FIG. 5 is a top view of another embodiment of a wound cover 24′, andFIG. 6A is a section view of the wound cover 24′ taken through line 6-6in FIG. 5, illustrating the wound cover 24′ in the rigid or raisedconfiguration. FIG. 6B is an enlarged section view of a portion of thewound cover of FIG. 5, defined by curve 6B-6B in FIG. 6A. Any of thematerials, sizes, geometries, or other configurations or featuresdescribed with respect to other wound covers in this application can beapplied, as suitable, to any embodiments of the wound cover 24′disclosed herein. In the illustrated configuration, the wound cover 24′can be integrally formed such that the channels 50′ and the member 66′(that can be flexible) are formed from a single piece of material orfrom two or more separate materials formed in the same process so as tobe seamlessly joined. However, the embodiment of the wound cover 24′illustrated in FIGS. 5 and 6 is not so limited. In some embodiments, thechannels 50′ could be formed in a separate process as compared to themember 66′ and adhered or bonded to, or otherwise attached to, themember 66′. In the illustrated embodiment, the openings 50 a′ can allowthe positive pressure provided by the conduit 54 to travel through thewound cover 24′ and fill all of the channels 50′.

In the illustrated embodiment, as positive pressure can be providedthrough conduit 54 to the channels 50′, the channels 50′ can be causedto expand. The channels 50′ can be configured such that, as they expand,they cause the bottom surface of the member 66′ to rise above and moveaway from the wound site 22. In the illustrated embodiment, the channels50′ can be relatively tall in profile (as best illustrated in FIG. 6A,6B), so as to provide a substantial amount of structural rigidity to thewound cover 24′ to keep the wound cover 24′ from collapsing on the woundsite 22 as negative pressure is being provided to the volume of space 68between the wound cover 24′ and the wound site 22. Additionally, in theillustrated embodiment, the channels 50′ can be relatively narrow inwidth so as to minimize the total volume of the channels 50′ so that thechannels 50′ can be quickly inflated and deflated to change the woundcover 24′ between a rigid and flexible type cover. Additionally, thechannels 50′ and other components comprising the wound cover 24′ can beconfigured such that, as the pressure is removed from within thechannels 50′, the wound cover 24′ become sufficiently flexible so as tocollapse over the wounds 22 when a negative pressure is supplied to thevolume of space 68 between the wound cover 24′ and the wound 22.

FIG. 7 is a top view of another embodiment of a wound cover 24″, andFIG. 8 is a section view of the wound cover 24″ taken through line 8-8in FIG. 7, illustrating the wound cover 24″ in the rigid or raisedconfiguration. Any of the materials, sizes, geometries, or otherconfigurations or features described with respect to other wound coversin this application can be applied, as suitable, to any embodiments ofthe wound cover 24″ disclosed herein. In the illustrated embodiment, thechannels 50″ can be formed separately as compared to the member 66″(that can be flexible) and can be adhered to or otherwise joined to themember 66″ by any suitable method. However, the embodiment of the woundcover 24″ illustrated in FIGS. 7 and 8 is not so limited. In someembodiments, the channels 50″ can be integrally formed with the member66″ so that the channels 50″ and the member 66″ are formed from a singlepiece of material or from two or more separate materials formed in thesame process so as to be seamlessly joined.

In some embodiments, the sheet or member 66″ can be sized and configuredto be placed over and enclose the wound 22 so as to define a space 68between the flexible sheet member 66″ and the wound 22 when the woundcover 24″ is in the raised configuration. In some embodiments, themember 66″ illustrated in FIG. 8, or any flexible member of anyembodiment of the wound cover disclosed herein, can be sized andconfigured so as to be generally unstretched when the flexible membraneis in the raised configuration, as illustrated in FIG. 8. In particular,in some embodiments, the flexible sheet member 66″ can be sized andshaped so as to define either a concave or convex shape when theflexible sheet member 66″ is in an unstretched state. In thisconfiguration, because the member 66″ preferably does not have to bestretched when the wound cover is changed from the collapsedconfiguration to the raised configuration, a smaller force can berequired to be exerted by the channels 50″ on the member 66″ to raisethe member 66″ to the raised configuration.

In some embodiments, as in the illustrated embodiment, the channels 50″can define a generally triangular shaped cross-section and arepositioned on the member 66″ in a generally crisscross pattern. However,the shape and positioning of the channels 50″ is not limited to theshape and positioning shown in FIG. 7. The wound cover 24″ can beconfigured such that the channels 50″ define any suitable shape and arepositioned at any suitable position on the wound cover 24″. In someembodiments, the channels in this or any other embodiment disclosedherein can define a semi-circular, triangular, square, rectangular, orany other suitable cross-section. As with the embodiments describedabove, the openings 50 a″ can be configured to allow the positivepressure, that can be provided by the conduit 54, to flow through thewound cover 24″ so as to fill all of the channels 50″. Additionally, asseen most clearly in FIG. 8, the height of the channels 50″ (representedby “t” in FIG. 8) can be uniform across the entire length of thechannels 50″. In some embodiments, the height of the channels 50″ can bevaried across the entire length of the channels 50″. For example, insome embodiments, the channels 50″ can be tapered such that the height tof any of the channels 50″ is greatest near the center of the woundcover 24″ and less near the periphery of the wound cover 24″.

In the illustrated embodiment, as positive pressure is provided throughconduit 54 to the channels 50″, the channels 50″ can be caused toexpand. The channels 50″ can be configured such that, as they expand,they cause the bottom surface of the member 66″ to rise above and moveaway from the wound site 22. In the illustrated embodiment, the channels50″ can be relatively tall in profile (as best illustrated in FIG. 8) soas to provide a substantial amount of structural rigidity to the woundcover 24″ to keep the wound cover 24″ from collapsing on the wound site22 as negative pressure is being provided to the volume of space 68between the wound cover 24″ and the wound site 22. Additionally, in theillustrated embodiment, the channels 50″ can be relatively narrow inwidth so as to minimize the total volume of the channels 50″ so that thechannels 50″ can be quickly inflated and deflated to change the woundcover 24″ between a rigid and flexible type cover. Additionally, thechannels 50″ and other components comprising the wound cover 24″ can beconfigured such that, as the pressure is removed from within thechannels 50″, the wound cover 24″ can become sufficiently flexible so asto collapse over the wounds 22 when a negative pressure is supplied tothe volume of space 68 between the wound cover 24″ and the wound 22.

Additionally, as illustrated in FIGS. 7 and 8, in some embodiments, thewound cover 24″ can comprise a peripheral channel 51 that can bepositioned so as to be adjacent to the perimeter of the wound cover 24″.The peripheral channels 51 can be configured to be inflated and deflatedwith conduit 55, and to define an inner airspace 51 a. The peripheralchannel 51 can be configured so as to be separate from the channels 50″so as to define a separate airspace. In this arrangement, the inflationand deflation of the peripheral channel 51 can be controlledindependently from the inflation and deflation of the channels 50″.However, in some embodiments, the peripheral channel 51 can beconfigured so as to be and fluid communication with the channels 50″.

In some embodiments, the peripheral channel 51 can be sized, positioned,and configured so as to selectively increase the structural rigidity ofthe peripheral edge of the wound cover 24″, so that the peripheralportion of the wound cover 24″ is biased to conform to the shape of theinflated peripheral channel 51. Therefore, in some embodiments, when theperipheral channel 51 is inflated, the wound cover 24″ can be betterequipped to be sealed to the healthy skin 58 surrounding the wound site22 without the use of an adhesive or other sealing material orcomponent.

As illustrated in FIG. 8, the peripheral channel 51 can be formed fromany of the materials disclosed above for any components of the woundcover 24 or channels 50. In some embodiments, the peripheral channel 51can be formed from the same material used to form the channels 50″ andcan comprise a similar cross-section as the cross-section of thechannels 50. In some embodiments, the peripheral channel 51 can define asemi-circular, triangular, square, rectangular, or other suitably shapedcross-section. In the illustrated embodiment, the peripheral channel 51can define a triangular cross-section. The peripheral channel 51 canalso be formed integrally with the flexible sheet member 66″, or can beformed separately and adhered to, laminated to, or otherwise attached toor supported by the flexible sheet member 66″. The peripheral channel 51can be configured to work with any of the wound covers disclosed herein,including the square, rectangular, ovular, or other shaped wound covers24 disclosed herein.

In some embodiments, the wound cover 24″ or any wound cover disclosedherein can be configured so that a peripheral portion of the wound coveris structurally supported in a different manner than as described aboveso as to maintain a desired shape even when channels 50 are deflated.For example, in some embodiments, a rigid or semi-rigid band of materialcan be supported by or attached to the wound cover 24 adjacent to orclose to the peripheral edge of the wound cover 24 in place of theperipheral channel 51. The rigid or semi-rigid band of material can beconfigured to increase the rigidity of the peripheral portion of thewound cover 24 so that the wound cover 24 can maintain a desired shapebased on the shape of the band of such material. In some embodiments,the band of material can be bendable or otherwise moldable so that amedical practitioner or user can shape the band of material toapproximately match the contour of the patient's body adjacent to thewound site. In such embodiments, the material can be configured toretain its shape after being bent or molded so that the shape of theband of material and the peripheral edge of the wound coverapproximately match the contour of the patient's body adjacent to thewound site. Additionally, these embodiments can be configured so that asupply of negative pressure through the conduit 46 to the volume ofspace 68 between the wound cover 24 and the wound site 22 create asuction seal between the wound cover 24 and the healthy skin 58 adjacentto the wound site 22. In other words, in some embodiments, the supply ofnegative pressure to the wound cover 24 can exert an adequate pressureon the wound cover 24 so as to sufficiently seal the wound cover 24 tothe patient's body without the use of an adhesive or other sealingmaterial.

Some embodiments of the negative pressure wound therapy apparatus 20 canbe configured so that the wound cover 24 can be changed from thesemi-rigid or raised configuration (i.e., the configuration shown inFIGS. 3a, 4a , and 5) to the collapsed configuration (i.e., theconfiguration shown in FIGS. 3b, and 4b ) by methods and/or techniquesother than through adjusting the air pressure of portions of the woundcover 24 as described above. For example, in some embodiments, one ormore strips of piezoelectric material or other length changing material(i.e., material that changes length when, for example, but not limitedto, heat or an electrical current is applied to such material) can besupported by, laminated to, or formed within a portion of the flexiblesheet member 66 of the wound cover. In these embodiments, the endportions of the length changing material or member can be supportedand/or such material or member can be configured so that at least themiddle portion of the length changing material or member would bend awayfrom the wound site when the length of such material or member isincreased. In some embodiments, the wound cover can be configured sothat, when the strip or strips of length changing material are bentupward, the flexible sheet member 66 which sealably encloses the woundsite 22 can be displaced upwardly.

FIG. 9 is a top view of an embodiment of a wound cover 24′″ comprising alength changing member. In some embodiments, the length changing membercan be formed from a piezoelectric material. In some embodiments, thelength changing member can be formed from a material that changes lengthin response to a thermal energy (i.e., heat) being supplied to thelength changing member. FIG. 10A is a section view of the wound cover24′″, taken through line 10A-10A in FIG. 9, illustrating the wound cover24′″ in a collapsed position or configuration. FIG. 10B is a sectionview of the wound cover 24′″, taken through line 10B-10B in FIG. 9,illustrating the wound cover 24′″ in a raised position or configuration.As mentioned, in some embodiments, the length changing member can beformed from a material that changes length in response to heat orthermal energy being applied to the material, or can be formed from anysuitable material that selectively and controllably changes length. Inembodiments where a thermally activated length changing material isused, the operating temperature of such material can be less than orequal to approximately 40 degrees Celsius.

In the illustrated embodiment, the wound cover 24′″ can comprise aflexible sheet member 66 that can be secured to a healthy skin 58surrounding the wound site 22 with adhesive 60. In the illustratedembodiment, the flexible sheet member 66 is circular in shape. However,the shape of the flexible sheet member 66 is not so limited. Theflexible sheet member 66 can define any shape disclosed above, or can beany other shape suitable or desired for the intended application.Similarly, the flexible sheet member 66 can be formed from any materialdisclosed above, or from any material that is suitable or desired forthe intended application.

In some embodiments, as in the illustrated embodiment, the wound cover24′″ can comprise a semi-rigid support member 70 that can be positionedapproximately adjacent to the peripheral edge of the flexible sheetmember 66 and a length changing member 72 that can be secured to the topsurface of the flexible sheet member 66 with one or more straps 74. Inthe illustrated embodiment, the support member 70 can generally definean annular shape and can be adhered to, laminated to, or otherwiseattached to the top surface of the flexible sheet member 66 using anysuitable method or material. In some embodiments, the support member 70can be impregnated within or formed integrally with the flexible sheetmember 66. In the illustrated embodiment, the support member 70 can havetwo pairs of opposing support tabs 76 configured to receive and supportthe end portions 72 a of the length changing member 72. The semi-rigidsupport member 70 and the support tabs 76 can be formed from a suitablerigid material and configured so as to retain their shape and/orrigidity when the length of the length changing member 72 increases. Inthis configuration, because the end portions 72 a of the length changingmember 72 can be held in a fixed position by the support tabs 76, whenthe length changing member 72 is increased (e.g., as a result of beingsubjected to an electric current or thermal energy), the length of thelength changing member 72 can increase, which can cause the lengthchanging member 72 to bend convexly. Thus, the support member 70, thelength changing member 72, and the support tabs 76 can be configured sothat the length changing member 72 will not deflect or bend concavely(i.e., toward the wound site 22) when the wound cover 24′″ is subjectedto a negative pressure.

In the illustrated embodiment, the length changing member 72 cancomprise two linear portions that are integrally formed or joined in themiddle so as to define a criss-cross pattern across the top of theflexible sheet member 66. In some embodiments, the length changingmember 72 can comprise less than or more than two linear portionsprojecting radially from a center point of the wound cover 24′″. In someembodiments, the length changing member 72 can define any shape orconfiguration that is suitable for the desired application. In theillustrated embodiment, the length changing member 72 can be formed froma piezoelectric material such that, when an electrical current issupplied to the positive electrodes 78 a whereby an electrical currentflows from the positive electrodes 78 a through the length changingmember 72 and out through the negative electrodes 78 b, the lengthchanging member 72 can increase in length as described above. This cancause the wound cover 24′″ to change from the generally collapsedposition (illustrated in FIG. 10A) to the generally raised position(illustrated in FIG. 10B).

In some embodiments, the length changing member 72 can be biased sothat, when the length changing member 72 bends, the length changingmember 72 deflects in a direction away from the flexible sheet member 66and the wound site 22 even when a negative pressure is supplied to thevolume of space 68 between the flexible sheet member 66 and the woundsite 22 (as illustrated in FIG. 10B). In some embodiments, as in theillustrated embodiment, the length changing member 72 can be formed in abent shape so as to define a bend in a direction away from the flexiblesheet member 66 when the length changing member 72 is in a relaxed state(e.g., before an electrical current has been applied thereto). Inparticular, with reference to FIG. 10A, the length changing member 72can be formed so that, when the length changing member 72 is in therelaxed state, the length changing member 72 is bowed so that the middleportion 72 b of the length changing member 72 is above the end portions72 a of the length changing member 72 when the length changing member 72is in the orientation depicted in FIG. 10A. In this configuration, thepre-bent shape of the length changing member 72 can biase the lengthchanging member 72 to bend in a direction away from the flexible sheetmember 66 and the wound site 22 as opposed to bending toward theflexible sheet member 66 and the wound site 22 when the length of thelength changing member 72 increases.

In the illustrated embodiment, the straps 74 can be sized and configuredto secure the length changing member 72 to the flexible sheet member 66.The straps 74 can be formed from the same or different material as isused to form the flexible sheet member 66, and can be formed integrallywith the flexible sheet member 66 or formed separately and adhered,fused, or otherwise attached to the flexible sheet member 66. In someembodiments, with reference to FIG. 10A, the straps 74 can be sized andconfigured to allow the flexible sheet member 66 to conform to the shapeof the wound site 22 so that, when the wound cover 24′″ is in thecollapsed position (as illustrated in FIG. 10A), the flexible sheetmember 66 can conform to the shape of the wound site 22 or wound packingmaterial, if any, positioned between the flexible sheet member 66 andthe wound site 22 even though the length changing member 72 is bowedaway from the wound site 22. Further, in some embodiments, withreference to FIG. 10B, the straps 74 can be sized and configured toposition the flexible sheet member 66 above the wound site 22 when thewound cover 24′″ is in the raised position (as illustrated in FIG. 10B)so as to increase the volume of space 68 between the flexible sheetmember 66 and the wound site 22 as compared to when the wound cover 24′″is in the collapsed position. In some embodiments, the size and numberof straps 74 can be selected according to the size and shape of theflexible sheet member 66 or the length changing member 72, or accordingto the size and shape of the wound site 22. In some embodiments, thelength changing member 72 can be adhered, laminated, or attacheddirectly to the flexible sheet member 66 such that the straps 74 are notrequired.

In some embodiments, the control device 32 can be configured to providean electrical current to the length changing member 72 throughelectrically conductive wires 80 that are connected to the positiveelectrodes 78 a. Further, electrically conductive wires 82 can beconnected to the negative electrodes 78 b to complete the electricalcircuit. In some embodiments, the amount of bending in the lengthchanging member 72 and, hence, the position of the wound cover 24′″relative to the wound site 22, can be controlled in part by themagnitude of the electrical current supplied to the length changingmember 72 by the control device 32. Therefore, in some embodiments, thecontrol device 32 can be used to control the position of the wound cover24′″ so that the wound cover 24′″ can be positioned in any of a widerange of positions between a generally collapsed position and agenerally raised position. In some embodiments, the control device 32can be configured to allow a user or medical practitioner to select themagnitude of the electrical current or otherwise control the position ofthe wound cover 24′″. In some embodiments, the control device 32 can beconfigured to change the position of the wound cover 24′″ according to apredetermined program or in response to input from a user or a sensor orother component, as described below.

Additionally, in some embodiments, any of the dressings, wound covers,or apparatuses disclosed herein can be configured so that the level ofpressure in the space between the wound cover and the wound can beregulated and controlled. For example, in some embodiments, the level ofpressure in the space between the wound cover and the wound can becontrolled so that the level of reduced pressure in the space does notsubstantially change when the wound cover is changed or moved betweenthe generally raised position to the generally collapsed position (i.e.,from the generally raised position to the generally collapsed positionor any positions therebetween, or from the generally collapsed positionto the generally raised position or any positions therebetween).

In some embodiments, the materials, size, and geometric configuration ofthe wound cover 24 (or any wound cover disclosed herein) can be chosenso that wound cover can remain flexible and compliant, and sufficientlyadhered to the body, so that the wound cover can flex with the movementof the portion of the body surrounding the wound and remain affixed tothe patient's body even when the wound cover changes from the raisedposition to the collapsed position or is inadvertently bumped, pulled,compressed, or otherwise impacted. Furthermore, in some embodiments, thewound cover 24, which in some embodiments can include the flexible sheetmember 66, channels 50, and/or peripheral channel 51, can be formed froma material that is sufficiently transparent to allow a medicalpractitioner or patient to visually inspect the wound site or woundpacking material without removing the wound cover 24 or a portion of thewound cover 24 from the body. In some embodiments, the visual inspectionof the wound site 22 or wound packing material can assist the medicalpractitioner patient in determining when to change the configuration ofthe wound cover 24 from the raised configuration to the flexibleconfiguration, or vice versa. Furthermore, any of the wound coversdisclosed herein can have any suitable shape or size in addition tothose disclosed herein including, but not limited to, rectangular,square, circular, ovular, triangular, trapezoidal, or any other desiredor suitable shape.

The negative pressure wound therapy apparatus 20 can be configured sothat the wound cover 24 can be changed from the raised configuration(e.g., the configuration shown in FIGS. 3a, 4a , and 5) to the collapsedconfiguration (e.g., the configuration shown in FIGS. 3b and 4b ) in anumber of different ways. In some embodiments, the wound cover 24 can bechanged from the semi-rigid configuration to the collapsed configurationas a result of manual input from a user or medical practitioner througha switch, button, lever, or other suitable switching mechanism.Similarly, in some embodiments, the apparatus 20 can be configured suchthat a medical practitioner or other user can adjust the amount ofpositive pressure or suction that can be applied by the pressure pump 52to the channels 50 of the wound cover 24. For example, in someembodiments, the pressure pump 52 and the vacuum system 26 can besupported within an enclosure having either a digital or analog set ofcontrols configured to allow the user to vary the positive pressuresupplied to the wound cover 24 or the amount of negative pressuresupplied from the vacuum pump 30 to the wound site 22. In someembodiments, the pressure pump 52 and the vacuum system 26 can becontrolled by the control device 32 to follow a predetermined program orcycle, wherein any or all of the values such as duration, magnitude ofthe positive pressure supplied to the channels 50, and the negativepressure supplied to the wound site 22, are generally preset orpredetermined, or are adjustable by the practitioner or user.

As mentioned, in some embodiments, the components of the apparatus 20,including but not limited to the switch mechanism discussed above andthe control device 32, can be configured to cycle the wound cover 24between the semi-rigid configuration and the collapsed configurationaccording to a predetermined duration or frequency or according to aduration or frequency as set by the practitioner or user. For example,in some embodiments, the wound cover 24 can be changed from thesemi-rigid configuration to the collapsed configuration approximatelyevery five minutes. In some embodiments, the wound cover 24 can bechanged as follows (though not so limited): alternating from thesemi-rigid configuration to the collapsed configuration or vice versaapproximately every 1 minute or less; or approximately every 1 to 5minutes, or approximately every 5 to 10 minutes, or approximately every10 to 20 minutes, or approximately every 20 to 40 minutes, orapproximately every 40 to 60 minutes, or approximately every 1 to 4hours, or approximately every 4 to 8 hours, or approximately every 8 to24 hours or longer, or to or from the any value within these ranges. Inaddition to the configurations disclosed herein where a user can controlthe switch mechanism or other settings of the apparatus 20, in someembodiments, the apparatus 20 can be configured to comprise patientlock-out features, i.e. features that prevent a patient or person otherthan the medical practitioner administering the negative pressure woundtherapy from adjusting or otherwise manipulating the switch mechanismsor other controls of the apparatus 20.

In some embodiments, the apparatus 20 can be configured to alternate thewound cover 24 at a non-uniform frequency between the rigid and theflexible configurations. For example, in some embodiments, the apparatuscan be configured so that the wound cover 24 is in the semi-rigidconfiguration approximately 10% or less of the time, or betweenapproximately 10% and approximately 20%, or between approximately 20%and approximately 30%, or between approximately 30% and approximately40%, or between approximately 40% and approximately 50%, or betweenapproximately 50% and approximately 60%, or between approximately 60%and approximately 70%, or between approximately 70% and approximately80%, or between approximately 80% an approximately 90%, or betweenapproximately 90% and approximately 100% of the time, while in thecollapsed configuration the remainder of the time. As an example of theabove listed ranges, a wound cover 24 with channels 50 inflated so thatthe wound cover 24 is in the semi-rigid configuration approximately 20%of the time means that, for every 1 minute that the wound cover 24 is inthe semi-rigid configuration, the wound cover 24 will be in thecollapsed configuration for approximately 4 minutes.

Although the apparatus 20 is not limited to the specific negativepressure ranges disclosed herein, the following are some of the typicalnegative pressure ranges that can beneficially promote wound healing orprovide other benefits related to negative pressure wound therapy. Forexample, in some embodiments, the apparatus 20 can be configured so thatthe apparatus 20 can provide, and so that the wound cover 24 canaccommodate, up to approximately 200 mmHg of negative pressure below theatmospheric level. It is to be understood that the values of negativepressure disclosed herein are relative to ambient pressure such that,for example, 200 mmHg of negative pressure would be approximately 560mmHg in practical terms (where the ambient pressure is approximately 760mmHg). In some embodiments, the wound cover 24 and other components ofthe apparatus 20 can be configured to provide greater than approximately200 mmHg of negative pressure to the wound site, although this level ofnegative pressure may exceed the generally desired range for most woundtherapy programs. For some embodiments of the apparatus 20, it may bedesired to provide in excess of approximately 200 mmHg of negativepressure to a dressing for purposes of examining the wound cover,conduit, pump system, or other components of the apparatus 20 for leaksor other performance-based deficiencies or characteristics.

In some embodiments, the apparatus 20 including the wound cover 24 canbe configured to provide as little as approximately 40 mmHg toapproximately 80 mmHg of negative pressure to the wound. This level ofnegative pressure, i.e., approximately 40 mmHg to approximately 80 mmHg,is typically associated with greater patient comfort and compliance.Additionally, some embodiments of the apparatus 20 and wound cover 24can be configured to provide and sustain less than approximately 40 mmHgat the wound site, although many wounds that are treated with theapparatus 20 would benefit from a greater level of reduced pressure.Some embodiments of the apparatus 20 can be configured to providenegative pressure levels in excess of approximately 80 mmHg, such aslevels up to approximately 150 mmHg. Further, as discussed above, someembodiments of the apparatus 20 and wound cover 24 can be configured toprovide a positive pressure (i.e., pressure in excess of atmosphericpressure) to the wound.

As discussed above, it may be particularly beneficial to provide apositive pressure to the wound cover 24 and, hence, the wound, tofacilitate changing the wound cover 24 from the flexible typeconfiguration or position to the semi-rigid configuration or position.In particular, some embodiments of the apparatus 20 can be configured toprovide up to approximately 200 mmHg or more of positive pressure (i.e.,approximately 200 mmHg above atmospheric pressure). Thus, someembodiments of the apparatus 20 and wound cover 24 can be configured toprovide between approximately 200 mmHg or more above atmosphericpressure to approximately 200 mmHg or more below atmospheric pressure.However, because providing positive pressure to the space between thewound cover 24 and the wound may affect the seal between the wound cover24 and the patient's healthy skin, the application of positive pressureto the wound cover 24 must be monitored closely and used carefully sothat the seal between the wound cover 24 and the skin is maintained. Forexample, in some embodiments, the apparatus 20 can be configured so thatchanging the wound cover 24 from the flexible to the semi-rigidconfiguration maintains approximately 100% to 50% of the level ofnegative pressure provided by the vacuum system 26 to the wound site.

Also, some embodiments of the apparatus 20 can be configured to permit amedical practitioner or user to set a maximum positive or negativepressure level that the vacuum system 26 of the apparatus 20 cannotexceed. Additionally, particular pressure ranges may be more suitablefor either the semi-rigid configuration or the flexible configuration.For example, for a particular patient and for a particular wound,beneficial operating pressures may depend on whether the wound cover 24is in the semi-rigid configuration or the collapsed configuration. Toaccommodate this, some embodiments of the apparatus 20 can be configuredso that the negative pressure levels provided by the apparatus 20 to thewound are dependent on the position or configuration of the wound cover24. As one non-limiting example, some embodiments of the apparatus 20can be configured such that the negative pressure level provided to thewound cover 24 in the semi-rigid configuration is between approximately60 mmHg-approximately 80 mmHg, while the negative pressure levelprovided to the wound cover 24 in the collapsed configuration is betweenapproximately 40 mmHg-approximately 60 mmHg. Additionally, someembodiments of the apparatus 20 can be configured such that a medicalpractitioner or user has the ability to adjust the level of the negativepressure applied to the wound based on the configuration of the woundcover 24.

In some embodiments, as will be described in greater detail below, theapparatus 20 can further comprise monitors or sensors such as, but notlimited to, temperature sensors, pressure sensors, blood flow sensors,blood oxygen saturation sensors, red blood cell perfusion sensors, ortranscutaneous oxygen tension sensors positioned within the wound bed oradjacent to the wound bed. In some embodiments, sensors for surfaceapplication (for example, for application to the dermis or wound bed)can be used. In some embodiments, sensors that are implantable in thebody or otherwise invasively applied, can be used. In particular, insome embodiments, the sensors can be positioned inside of the woundcover so as to be positioned between the wound cover and the wound. Insome embodiments, the sensors can be positioned at least partiallywithin the wound cover or, in some embodiments, positioned outside ofthe wound cover 24 preferably on the surface of or implanted within thehealthy skin adjacent to the wound 22.

As mentioned, in some embodiments, the sensor or sensors can include,but are not limited to, sensors that can detect the temperature of thewound and/or blood flowing into the wound, the pressure within the woundcover, the rate of blood flowing into or adjacent to the wound, or thegas content of blood flowing into or adjacent to the wound, such gasesincluding but not limited to oxygen, carbon dioxide, or other bloodgases typically present in the body. Additionally, transcutaneousoximetry apparatuses and sensors used to detect transcutaneous oxygentension in or adjacent to the wound bed can incorporated into any of thesuitable embodiments of the apparatus 20 or used with any of thesuitable wound covers 24 disclosed herein.

Any sensor presently known in the art that can be used to measure theparameters disclosed herein or other parameters of interest can be usedwith any of the embodiments of the apparatus 20 or wound cover 24disclosed herein. Such sensors can include, but are not limited to, theapparatus for blood gas monitoring disclosed in U.S. Pat. No. 6,856,821(titled “SYSTEM FOR COMBINED TRANSCUTANEOUS BLOOD GAS MONITORING ANDVACUUM ASSISTED WOUND CLOSURE”), issued on Feb. 15, 2005 andincorporated by reference as if fully set forth herein. Additionally,without limitation, the pulsed light and blood oxygen content sensorsystem set forth in U.S. Pat. No. 5,040,538 (titled “PULSED LIGHT BLOODOXYGEN CONTENT SENSOR SYSTEM AND METHOD OF USING SAME”), issued on Aug.20, 1991 and incorporated by reference as if fully set forth herein, canalso be used with the embodiments of the negative pressure wound therapyapparatus 20 described herein to determine the blood oxygen contentwithin or adjacent to a wound site. Additionally, the transcutaneousoxygen monitor or monitors described in “Wound Healing Perspectives—AClinical Pathway To Success”(http://www.nationalhealing.com/downloads/nhcwhpspring04.pdf), Volume 1,No. 4, Spring 2004, published by the National Healing Corporation whichis incorporated by reference as if fully set forth herein, can be usedwith, or easily adapted for use with, any of the embodiments of theapparatus 20 or wound cover 24 disclosed herein.

Additionally, any sensor presently known in the art or later developedthat can be used to measure the flow of blood or the perfusion of redblood cells into or adjacent to the wound site can be used with any ofthe embodiments of the apparatus 20 or wound cover 24 disclosed herein.Such sensors can include, but are not limited to, the OxyFlo2000, theOxyFlo4000, OxyLab LDF laser Doppler tissue blood perfusion monitors, orlaser Doppler blood flow probes developed by Discovery TechnologyInternational, LLLP (http://www.discovtech.com/PAGE1.htm), any of whichmay be suitable for use with any of the embodiments of the apparatus 20or wound cover 24 disclosed herein. In some embodiments, ultrasonicblood flow measurement devices which, in some cases, are based on thelaser Doppler technology, can be adaptable for use with the presentembodiments to be used to measure of the flow of blood into the tissuein the wound bed or adjacent to the wound site.

Capillary laser Doppler devices that are implanted within the wound siteor adjacent to the wound site may provide the most accurate readings ofblood flow or the perfusion of red blood cells into or adjacent to thewound site. Further, in some embodiments, transfused blood oxygensensors that are currently available in the art or that are laterdeveloped can be configured for use with the apparatus 20. In someembodiments, the transfused blood oxygen sensors may need to becalibrated or adjusted for the operating pressure at the wound site toyield accurate data. The calibration for the operating pressure at thewound site could be programmed into the control device or other devicethat controls the sensors and/or collects the data gathered by thesensors. In some embodiments, it may be possible to measure transfusedcarbon dioxide levels using such sensors.

Because the semi-rigid configuration can increase the amount of bloodflow to the wound site 22 at a particular negative pressure value ascompared to the collapsed configuration, merely changing the wound cover24 from the flexible configuration to the semi-rigid configuration canresult in a blood flow increase to the wound site 22. Lack of sufficientblood flow to the wound site 22 is one reason why chronic wounds do notheal optimally. Conversely, in some embodiments, the collapsedconfiguration can exert a physical contact pressure on the tissue at thewound sites 22 so as to partially close the capillaries, arteries, orother blood vessels so that the blood flow rate to the wound sitedecreases. This may be advantageous when the wound is aspirating at ahigher than desired rate.

In some embodiments, the sensors can be used to automatically triggerthe control device 32 to change the wound cover 24 from the semi-rigidconfiguration to the collapsed configuration once the readings from thesensors reaches a particular or predetermined value (i.e., a thresholdor trigger value), such as but not limited to preprogrammed values orchanges in values related to blood flow or blood oxygen saturationlevels. For example, in some embodiments, the threshold value that cantrigger the change in the configuration of the wound cover 24 can bebased on changes in the sensor readings (such as, but not limited to,changes in blood flow rate or blood oxygen saturation level) as comparedto optimal or average values in the patient's body at or near the woundsite or at another suitable bodily location. As such, in someembodiments, the trigger or predetermined value can be based on changesdetermined at the wound site from the sensors or can be based on thedifference between the values determined at the wound site compared tovalues determined by suitable sensors at another bodily location. Thetrigger or predetermined value or values can be based on changesdetermined at the wound site or at another bodily location relative toreadings taken prior to or during the negative pressure wound therapy atthe wound site or at another bodily location.

Accordingly, in some embodiments, when the measurements (such as bloodflow rate or rate of aspiration of exudate) acquired by the sensor orsensors exceed an optimal or predetermined value, the apparatus 20 canbe configured so that the wound cover 24 is changed to the, or remainsin the, collapsed configuration until the blood flow rate to the woundsite 22 falls to a predetermined or suitable level. For example, in someembodiments, when the blood flow rate or the rate of aspiration ofexudate from the wound determined by the appropriate sensor exceedsapproximately 120% of the patient's optimal or average blood flow rateor aspiration rate, the apparatus 20 can be configured so that the woundcover 24 is automatically changed to the, or remains in the, collapsedconfiguration until the blood flow rate or aspiration rate falls below aparticular value—which can be 120% of the patient's optimal or averagerate, or another predetermined relative value. In some embodiments, theapparatus 20 can be configured so that the wound cover 24 isautomatically changed to the, or remains in the, collapsed configurationwhen the value determined by the sensor exceeds approximately 110% orless, or from approximately 110% to approximately 120%, or fromapproximately 120% to approximately 130% or more of the patient'soptimal value or average bodily value. The patient's optimal value maybe determined as the optimal value at the wound site, or may be anoptimal value based on sensor readings at other bodily locations.Additionally, the control device 32 can be configured to control thelevel of negative pressure between the wound cover 24 and the wound 22depending on the value determined by the sensor or sensors. Further, asdiscussed in greater detail below, the apparatus 20 can be configuredsuch that an alarm is triggered when such threshold values are reached.

Similarly, in some embodiments, when the measurements (such as bloodoxygen saturation, temperature, or red blood cell perfusion rate)acquired by the sensor or sensors drop below an optimal or predeterminedvalue, the apparatus 20 can be configured so that the wound cover 24 ischanged to the, or remains in the, raised configuration until therespective value increases to a predetermined or suitable level. Forexample, in some embodiments, when the blood oxygen saturation,temperature, or red blood cell perfusion rate determined by theappropriate sensor drops below approximately 80% of the patient'soptimal or average value, the apparatus 20 can be configured so that thewound cover 24 is automatically changed to the, or remains in the,raised configuration until the readings for the respective valueincreases to or above a particular value—which can be 80% of thepatient's optimal or average value, or another predetermined relativevalue. In some embodiments, the apparatus 20 can be configured so thatthe wound cover 24 is automatically changed to the, or remains in the,raised configuration when the value determined by the sensor drops belowapproximately 90% or greater, or from approximately 90% to approximately80%, or from approximately 80% to approximately 70%, or fromapproximately 70% to approximately 50% or less of the patient's optimalvalue or average bodily value. The patient's optimal value may bedetermined as the optimal value at the wound site, or may be an optimalvalue based on sensor readings at other bodily locations.

As mentioned, in some embodiments, the threshold or trigger valuesdisclosed herein can be based on changes in such values determined bythe sensors at the wound site or the difference between the value orvalues determined by the sensors at the wound site as compared to otherbodily locations. The control device 32 can be configured to calculatesuch differences and determine when the threshold or trigger value hasbeen reached. In some embodiments, however, the threshold or triggervalues can be a straight forward value preprogrammed into the controldevice 32, or can be input by the user or practitioner of the apparatus20.

FIG. 11 is a schematic representation of a portion of the apparatus 20in which a pair of sensors 84 can be positioned in the wound bed 22.Note that, in FIG. 11, the wound cover 24 is shown in the deflated orcollapsed configuration. By inflating the channels 50, the wound cover24 could be changed from the collapsed configuration to the semi-rigidconfiguration. The wound cover 24 can be secured to the healthy skinsurrounding the wound with adhesive (not shown) or by any other suitablemethod. Either of the sensors illustrated in FIG. 11 can be atemperature, pressure, blood flow, or blood oxygen saturation levelsensor, or other any other suitable sensor currently available or laterdeveloped. As illustrated in FIG. 11, the sensors 84 can be connected tothe control device 32 via leads 86. The leads 86 can be cables or wiresconstructed of an electrically conductive material, optical fiber, orother suitable medium arranged to enable data transmission from thesensors 84 to the control device 32, alarm device 88, recording device90, and/or a visual display (not shown). The leads 86 can be sealablyrouted under the wound cover 24 in a manner that is similar to that forthe conduit 46 so as to maintain the gas and fluid impermeable orsemi-impermeable nature of the seal of the wound cover 24 to the body.

In some embodiments, only one sensor 84 can be positioned in the woundbed 22, but the apparatus 20 is not so limited. In some embodiments, anynumber of sensors 84 can be positioned in the wound bed 22. Withreference to FIG. 11, the apparatus 20 can comprise a control device 32,an alarm device 88, and/or other recording device 90. In someembodiments, however, the apparatus 20 can comprise only the controldevice 32. The control device 32 can receive signals from the sensors 84and converts the signals to an electronic or other suitable form thatcan be recognized by the alarm device 88. Accordingly, neither the alarmdevice 88 nor the recording device 90 is required in some arrangementsof the apparatus 20. The alarm device 88 and the recording device 90 aresupplemental components that can be added to the apparatus 20 to warnthe user or practitioner when the values determined by the sensors 84exceed predetermined values associated with the sensors 84, and torecord the values transmitted from the sensors 84 over a predeterminedamount of time, respectively. As such, the apparatus 20 illustrated inFIG. 11 can operate without the addition of the alarm device 88 and/orrecording device 90.

The alarm device 88 can produce any type of audible sound whenactivated, such as a ringing sound, buzzing, chirping or any othercommon alarm noise. Alternatively, the alarm device 88 can include adigitally produced audible voice that presents pre-arranged messagescorresponding to different conditions in the area of the wound site 22.The alarm device 88 can produce different levels of the alarm dependingupon the magnitude of the measurements received from the sensors 84. Forexample, if the blood flow rate or temperature drops below or risesabove predetermined values, as measured by the sensors 84, the alarmdevice 88 can sound successive alarm pitches, sounds, messages or seriesof sounds. Similarly, as the blood oxygen saturation level measured byany of the one or more sensors 84 falls below or rises above apredetermined value, the apparatus 20 can be configured to alert theuser. As mentioned above, the control device 32 can also control thevacuum 30 or the positive pressure pump 52 to either adjust the negativepressure under the wound cover 24, or positive pressure in the channels50 in the wound cover 24, respectively, so that the negative pressureunder the wound cover 24 or the configuration of the wound cover 24 canbe adjusted in response to the data collected by the sensors 84.

The recording device 90 can be any device designed to record datareceived from the sensors 84. Such devices can be capable of recordingdata on compact disks, DVD disks, floppy disks, magnetic tape,integrated circuits, or other similar media in digital form.Alternatively, the recording device 90 can be a “manual” device thatrecords or displays data through a chart recorder or visual electronicdisplay, such as an LCD or CRT monitor. Such information can be in theform of real-time data, or an average over a predetermined duration oftime, or any other suitable form. In some embodiments informationregarding blood flow could be displayed as follows: (i) Blood FlowSteady; (ii) Blood Flow Increasing; or (iii) or Blood Flow Decreasing.In some embodiments, information regarding blood oxygen saturation levelcould be displayed as follows: (i) Oxygen Level Steady; (ii) OxygenLevel Increasing; or (iii) or Oxygen Level Decreasing. Thus, theapparatus 20 or display could embody this information that is beinggathered by one or more of the sensors 84 to help with the wound healingas well as provide important information to a health care practitionerstudying the effects of such parameters on wound healing.

FIG. 12 is a schematic representation of a portion of the apparatus 20in which multiple sensors 84 are positioned on the inside surface of themember 66 of the wound cover 24. As is illustrated, the wound cover 24is shown in the rigid or raised configuration. In some embodiments, thesensors 84 and/or leads 86 can be adhered to the inside surface of themember 66, or otherwise supported by the member 66. Alternatively, insome embodiments, the sensors 84 and/or leads 86 can be integrated intothe member 66 during the manufacture of the wound cover 24. For example,the sensors 84 and leads 86 can be placed between one or more layerscomprising the member 66 so as to be formed integral therewith. Ifnecessary, the portion of the material comprising that member 66 that isadjacent to the sensors 84 can be removed prior to use so that thefunctionality of the sensors 84 will not be obstructed or attenuated bythe material in the wound cover 24. The sensors 84 and leads 86 can besized and configured so as to not irritate or otherwise damage any ofthe tissue in or around the wound bed 22 when the wound cover 24 ischanged from the semi-rigid configuration (as shown in FIG. 12) to thecollapsed configuration. In some configurations, the sensors 84 andleads 86 can be covered with a cotton gauze or other suitable materialthat will not affect the sensors ability to collect the desiredinformation from the wound bed 22, but that will protect the wound bed22 from any damage that may occur if the sensors 84 or the leads 86contact the wound bed 22.

In some embodiments, not shown, one or more of the sensors 84 can bepositioned within the absorbable matrix or other dressing materialpositioned within the wound bed. Alternatively, in some embodiments, oneor more sensors 84 can be positioned on or in the fluid collectionsystem 28 to change the configuration of the wound cover 24 from a rigidconfiguration to the flexible configuration when the rate at whichexudate enters the fluid collection system 28 exceeds a predeterminedvalue. As mentioned above, the blood flow through the wound site 22,and, accordingly, the exudate produced by the wound may be lower whenthe wound cover 24 is in the collapsed configuration than when the woundcover 24 is in the semi-rigid configuration. Additionally, the apparatus20 can be configured such that the amount of negative pressure suppliedto the wound site 22 is decreased when the amount of exudate in thefluid collection system 28, or the rate at which exudate flows into thefluid collection system 28, exceeds predetermined values.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the device or process illustrated can be madewithout departing from the spirit of the disclosure. Additionally, thevarious features and processes described above can be used independentlyof one another, or can be combined in various ways. All possiblecombinations and subcombinations are intended to fall within the scopeof this disclosure.

As will be recognized, certain embodiments disclosed herein can beembodied within a form that does not provide all of the features andbenefits set forth herein, as some features can be used or practicedseparately from others. The scope of the inventions is indicated by theappended claims rather than by the foregoing description. All changeswhich come within the meaning and range of equivalency of the claims areto be embraced within their scope.

1. An apparatus for covering a wound and facilitating the application ofnegative pressure wound therapy to the wound, comprising: a wound coverconfigured to be placed over and enclose the wound so as to define aspace between at least a portion of the wound cover and the wound and tomaintain a reduced pressure in the space when reduced pressure isapplied to the space; wherein when the wound cover is placed over andencloses the wound and reduced pressure is applied to the space, thewound cover is configured to move between at least a raised position anda collapsed position without substantially changing the level of reducedpressure in the space; and a volume of the space between at least aportion of the wound and the wound is greater in the raised positionthan in the collapsed position. 2-77. (canceled)